Air-compressor pump.



G. & C. BURD.

AIR COMPRESSOR PUMP. I

APPLlcAnoN HLED oc.18.1917.

1 ,273,728. Patented July 23, 1918,.

O 6 if D l N 11W *D SO l N N Q1 N i m) QU l I Y Y Y wom/MomsA UNITED s'iiirns PATENT' OFFICE.

I GEORGE BUBD AND CHARLES BUIBJJ,v 0F HAZELWOOD, PENNSYLVANIA.

Ain-coMPnEsson rum.

Bpeclcation of Letters .Patcnt.

' Patented July 23, 1918.

Application led October 18, 191'?.` Serial No. 197,234.

p To all whom it may concern Be it known that we, GEORGE BURD 'and CHARLES -BURIp citizens of the UnitedStates -drawin This invention relates to improvements inv air compressor pumps, and the improvement is adapted to loe-used either as a single or a double compressor.

Among the objects of my invention are:

1. Providing a hollow'piston into which the air is drawn and compressed, whereby the hollow compression piston is subjected to the cooling effectof the air when withdrawn from the cylinder on its outstroke,

which rapidly radiates its heat and prevents air, the wall of the cylinder having a thickness less than the 'width of the annular cylinder in which it enters, and the open end of the cylinder provided with a packing engaging the exterior of the hollow piston to make an air-tight fit, whereby friction occurs only at the point of the packing, thus reducing the tendency to heat up, and whereby the hollow piston is exposed to the air at each outstroke to be cooled.

4. Providing a compressor composed of oppositely extending hollow pistons adapted to enterannular cylinders alternately for compressing the air in first one hollow piston and then the other. 'c

Other and more specific obJects of the 1nvention will appear from the following description.

The accompanying drawing 1s a horizontal sectional view of a compressorembodying my invention, the piping and receiving chamber being shown in top elevation.

We here show our improvement in the form of a double acting compressor, but

our invention is adapted forv use in a single acting compreor.

In the drawings, 1 represents two cylin.

ders. Each of these cylinders comprises an outer annular wall 2, and an inner annular wall 8. The outer ends of the inner and outer walls are closed by an annular wall 4, and the inner end of the annular wall .3

is closed by a head or wall 5, the walls 2 and 3 constituting between them the annular piston receiving space 6.

Coperating with this annular cylinder, thus constructed, is a hollow annular piston 7 having an outer open end 8. The wall of this hollow' piston is made thinner than.

the annular space 6, whereby the hollow piston may move back and forthl therein without engaging the walls of the annular cylinder. For the purpose of making an airtight lit, between the outer `surface of the hollow piston 7 and the open end of the annular cylinder, a suitable packing 9 is provided, which is annular or ring-like in shape and may be of any suitable form or construction. As here shown, this packing is of a fibrous character of some well-known suitable material, but it may be of any eicient metallic packing without ydeparting -from the spirit 'of my invention. This packing 9 is held in place by an annular ring 10 and suitable bolts 11. y

The difference between the thickness of the wall of the hollow piston 7 and the width of the space between the walls'2 and 3 is here exaggerated since they can be nearer to corresponding size than here shown, without departing from the spirit of my invenlwhich will permit air to be ydrawn therefrom into the hollow piston when it is drawn outward, and will close when the piston moves inward for compressing the air therein. This head 5 is also provided with an air-outlet opening or pipe 14, which is.

provided with a suitable outlet check valve 15, which will permit the air to be forced out by the compression of the hollow piston,

4but prevents air from passing therethrough .or pipe 17. The hollow piston may be reciprocated in any suitable manner. The way here shown, however, consists in providing the head 18 of the hollow piston with oppositely extending pintles 19 to which one end of the pitman or links 20 are swiveled at 2l. The other ends of these links 20 are swiveled at the points 22 to the crank arms 23, which are connected to a suitable crank shaft 24. This crank shaft 23 may be driven in any suitable manner, but, as here shown, it is provided with a gear wheel 25, geared to a wheel 26 carried by a suitable drive shaft 27. This drive shaft 27 may be driven by any form of power (not shown) such as a steam engine, an electric engine or explof sion engine.

Thus far we have described only a single compressor' embodying our invention, and that may lbe driven differently from the manner here'shown `without affecting the invention herein involved. However, our imrovement involves providing the piston cad with two hollow pistons which extend L in opposite directions and preferably .directly in a line with each other and coperating with an annular cylinder the same as that heretofore described, and since the hollow pistons and the annular cylinders are exactly alike, it is unnecessary to repeat the description heretofore given of one compressor, and the same reference letters are applied to both pistonsand both cylinders, the improvement in this respect belng a single piston head with oppositely extending hollow pistons coperating with cylinders spaced at opposite sides of the piston head and distances apart a little less than the length of the hollow portion of the two pistons.

Attention is directed to the fact that the hollow pistons are of such length and the cylinders placed a distance apart so that when `the ends of the links 20 are detached from the pintles 19, one .piston may be moved within its cylinder sutliciently far to carry the hollow end of the other piston outside of the packing 9, whereby the packing can be removed by removing the annular ring 10, and a new packing substituted therefor.

Projecting from opposite sides of each annular cylinder are the flanges 28, by means of which the cylinders may be attached to any suitable support.

By this construction both the inner and outer walls 2 and 3 of the annular cylinder are subjected to the cooling effect of the surrounding air as well as the hollow pistons when they are withdrawn from their respective cylinders and thus materially assist in preventing the overheating of the compressor in operation.

Having thus described our invention what we claimV and desire to secure by Letters Patent is An air compressor comprising two separate annular cylinders in a line with each other and having facing open ends, the inner wall of each cylinder having an inwardly projecting head with inlet and outlet openings, two connected hollow pistons coperating with the hollow cylindersI` the walls of the pistons being thinner than the spaces between the walls of the annular cylinders, packings carried by the ends of the outer walls of the cylinders and engagingv v the outer surfaces of the pistons, the packings supporting the pistons out of contact with the walls of the cylinders and making a tight joint between the outer walls of the cylinders and outer surfaces of the pistons. and means for reciprocating the pistons.

In testimony whereof we hereunto aiix our signatures in the presence of two witnesses.

GEORGE BURD. CHARLES BURD.

Witnesses:

JAMES F. KEOUGH, EDWARD A. FAUsT. 

